Unravelling the mystery in a case of persistent ACTH-independent Cushing's syndrome.

Background: We present a rare variety of adrenocorticotrophic hormone (ACTH)-independent Cushing's syndrome known as primary pigmented nodular adrenocortical disease (PPNAD).

Methods: The patient initially underwent unilateral adrenalectomy for what was thought to be a left adrenal adenoma.

Results: Partial resolution of symptoms and demonstrable persistent hypercortisolism after surgery prompted further evaluation with findings leading to the diagnosis of Carney complex. A review of the adrenal histology was consistent with PPNAD.

Conclusions: This entity of PPNAD, which has rarely been reported in Asians, forms part of the Carney complex. The diagnosis may not be simple and straightforward, as illustrated in this patient.